Cor a 14 is one of the most vital allergens in hazelnuts. However, the features of intestinal metabolites and microbiota associated with Cor a 14-induced allergy remain unclear. In this study, we established a hazelnut Cor a 14-allergic BALB/c mice model, which was distinguished by the dropped temperature and enhanced allergic inflammatory factor levels in serum. Faeces were collected to detect characteristics of the intestinal metabolites by untargeted metabolomics and the gut microbiota by 16S rRNA sequencing. The α- and β-diversity of gut microbiota in Cor a 14-allergic mice differed from the controls with elevated relative abundance of Lactobacillus and reduced relative abundances of Odoribacter, Chloroplast, Alistipes and Lachnospiraceae_NK4A136_group. Untargeted metabolomics results revealed that 238 significantly differential metabolites (111 up-regulated, 127 down-regulated) were identified, of which, L-tryptophan, histamine and N-acetylhistamine were remarkably accumulated and primarily enriched in the enhanced L-tryptophan and histidine metabolism pathways. Spearman correlation analysis suggested that L-tryptophan was positively correlated with allergic indicators and screened as the potential biomarker for Cor a 14 allergy. Collectively, our findings uncovered the characteristics of intestinal metabolites and gut microbiota during Cor a 14 anaphylaxis and provided new potential insights for diagnosis of hazelnut allergy.

Intestinal immune homeostasis plays a critical role in the pathogenesis of food allergy (FA). However, the association between intestinal microenvironment factors and FA severity is not well studied. In this study, we established a gluten allergy (GA) BALB/c mouse model and revealed the intestinal luminal factor-mediated alterations in phenotypes and endotypes of GA, combined with untargeted metabolomic profiling of the colonic contents. Our results showed that gluten sensitization induced severe allergic responses in BALB/c mice, characterized by exacerbated clinical allergic and diarrheal symptoms, increased histamine, elevated gluten-specific IgE and IgG2a levels, and increased mast cell degranulation. In response to GA, T-cell balance was disrupted, with aberrant production of IL-4, IFN-γ, IL-10, and IL-2 in the spleen. GA led to a disrupted intestinal microenvironment homeostasis, including increased pH and water content, impaired intestinal antioxidant capacity and epithelial barrier function, decreased short-chain fatty acid production, and microbial dysbiosis, which was strongly correlated with GA severity. By metabolomic profiling, we found 29 differential expressed metabolites (DEMs) associated with GA, with 9 down-regulated and 20 up-regulated. A total of 11 out of all DEMs were classified into dipeptides, and 10 of them were up-regulated in the gluten-allergic mice. Pathway enrichment analysis showed that most of the DEMs were enriched into the bile secretion metabolic route.

Increasing incidences showed that food allergies have attracted more and more attention from researchers. BALB/c mice were sensitized with wheat gluten combined with aluminum hydroxide adjuvant via intraperitoneal injection, transdermal sensitization, and oral gavage sensitization route. Results showed that all the three sensitization methods could induce allergic symptoms; increase the serum antibody (total immunoglobulin E (IgE), specific IgE, IgG, IgA) and histamine content; promote the secretion of Th2 cytokines (interleukin (IL)-4, IL-5, IL-13) and inflammatory factors (IL-6, IL-17A, IL-10); and inhibit the production of Th1 cytokines (IFN-γ, IL-2). However, the allergic symptoms of mice sensitized by intraperitoneal injection were the most obvious among the three models. The level of serum antibodies in intraperitoneal injection group was significantly higher than control. Subsequently, 16S rRNA sequencing technology was used to analyze the intestinal flora of mice. The results showed that the abundance of Firmicutes in the wheat protein sensitized group was lower than that in the normal group, while the abundance of Bacteroidetes was higher, and Lactobacillus was the difference marker in normal group. Bacterial species diversity analysis showed that the species richness and diversity of intestinal flora in mice were decreased, the difference between mice induced by intraperitoneal injection and normal control group mice was the most significant. Taken together, these results show that among three sensitization methods used to build a mouse model with aluminum hydroxide as adjuvant, intraperitoneal injection is the comparably best way to build a mouse sensitization mode.

High oleic-acid peanuts are known for their pre-longed shelf-life and health benefit due to high content of oleic fatty acid. However, the allergenicity and allergenic protein profiles in Chinese high-oleic peanuts have yet to be studied. For this purpose, an Orbitrap Fusion mass spectrometry (MS)-based method that is feasible for identification of putative allergenic protein as well as semi-quantitation of five major allergen protein in three different Chinese high-oleic peanut cultivars (JH 13, JH 16 and JH 18) have been reported. Results show that three Chinese high-oleic acid peanut cultivars selected all contained highly allergenic proteins Ara h 1, Ara h 2, Ara h 3 and Ara h 6. The allergenic protein profiles of Chinese high-oleic acid peanut cultivars were very similar to that of conventional peanuts, but the allergenic protein subunits varied greatly among high-oleic peanuts. Additionally, a comprehensive peptide-filtering pipeline had been developed for identification of potential peptide markers in peanut allergen proteins. Through the peptide-filtering pipeline, three novel peptide markers, IVQIEAKPNTLVLPK, SSNPDIYNPQAGSLR and AQSENYEYLAFK surrogate to Ara h 1, Ara h 3 with high abundance, good MS response and highly reliability were identified, which can be used as candidate peptide markers for the detection of peanut allergens in different food matrices.

With the prevalence of food allergy increasing every year, food allergy has become a common public health problem. More and more studies have shown that probiotics can intervene in food allergy based on the intestinal mucosal immune system. Probiotics and their metabolites can interact with immune cells and gut microbiota to alleviate food allergy. This review outlines the relationship between the intestinal mucosal immune system and food allergy. This review also presents the clinical application and potential immunomodulation mechanisms of probiotics on food allergy. We aim at providing a reference for further studies to explore the key active substances and immunomodulation mechanisms of anti-allergic probiotics.

Emerging evidence indicated that the increase in food allergy (FA) over the past few decades was associated with the abnormal compositional and metabolic changes of gut microbiota. Gut microbiota played a vital role in maintaining the homeostasis of the immune system and the dysbiosis of gut microbiota promoted the occurrence of FA. Recent research suggested that short-chain fatty acids (SCFAs), the main metabolites derived from gut microbiota, contributed to FA protection. Herein, we provided a comprehensive review on the relationship between gut microbiota and FA. The multifaceted mechanisms underlying beneficial effects of gut microbiota composition/metabolites on the regulation of diverse cellular pathways in intestinal epithelial cells, dendritic cells, innate lymphoid cells, T cells, B cells and mast cells in the immune system were discussed systematically. These findings emphasized the positive function of gut microbiota in FA and provided novel ideas for the treatment or prevention of FA in the future.